1. Field of the Invention
The present invention relates to the hub body for a spokes wheel, such as a bicycle wheel in particular. The invention also relates to a hub having such a hub body, as well as a spoked wheel including such a hub.
2. Description of Background and Relevant Information
In a known manner, a bicycle wheel includes a rim, a hub, and spokes for connecting the rim to the hub. In addition, the spokes are usually adjustable in tension.
Bent spokes and radial spokes are known among the commonly used spokes. Usually, a hub provided with bent spokes has two lateral disks, or disk-shaped portions, oriented in radial planes. The spokes are fitted into borings of the disks.
For radial spokes, the spoke head is retained by a surface portion of the flange that is oriented parallel to the hub axle.
To retain the spoke head, a closed boring can be obtained on this surface portion. In this case, the spoke must be fitted into this boring along a radial direction. Such a method for mounting the spokes is complex to carry out; indeed, the spoke, when being fitted, interferes with the hub shaft. Moreover, such a closed boring is not compatible with a double head radial spoke.
Another solution consists of retaining the spoke head in the area of an aperture. The aperture can be obtained in the wall of the flange, for a radial spoking method, or in the area of radially extending projections for a crossed spoking method. Each spoke is positioned in its aperture with a minimum of necessary displacement. The spoke mounting operation is indeed simplified.
Because the aperture is an open boring, it is capable of deforming more easily under the effect of the spoke tension. It is then necessary to reinforce the wall thickness or to add an additional washer or ring to achieve a satisfactory level of resistance to tearing. Such a ring is described, for example, in the published patent application No. EP 764 551.
Another solution consists of obtaining buttonhole-shaped borings having a portion with a large cross-section for engaging the spoke head, and a portion with a small cross-section for retaining the spoke.
However, such a boring proves cumbersome because of the portion with a large cross-section.
The published patent application No. DE 36 12 772 proposes a solution that consists of obtaining the large cross-section and the small cross-section of the buttonholes in two different planes, the portion with a large cross-section being bored in a radial portion of the flange.
However, the construction proposed is not completely satisfactory. Indeed, the portions with a large cross-section are closer to the hub axle than the portions with a small cross-section. As a result, they are relatively close to one another, which diminishes the rigidity of the flange. Furthermore, the portions with a small cross-section which retain the spoke heads are relatively distant from the axle. Therefore, relatively thick flanges are necessary to achieve a satisfactory rigidity.
An object of the invention is to propose an improved hub body and hub in the sense that they facilitate the assembly operations, are smaller sized, and are resistant and lightweight.
Another object of the invention is to propose a hub body that is easy to construct.
Other objects and advantages of the invention will become apparent from the following description.
The hub body according to the invention includes two lateral flanges having buttonhole-shaped borings provided for hooking the spokes with a portion with a large cross-section and a portion with a small cross-section. According to the invention, at least one of the flanges includes an approximately axial barrel extended by a disk, and the portion with a large cross-section is located in the area of the disk and the portion with a small cross-section in the area of the barrel, the portion with a small cross-section being located at the base of the portion with a large cross-section, with reference to the direction in which the spoke exerts a traction on the flange when it is mounted and tensioned.
The hub according to the invention includes a shaft and a hub body as previously described.
The borings are generally buttonhole-shaped, the spoke heads being introduced in the portion with a large cross-section, and the spoke being retained in the portion with a small cross-section. Therefore, the mounting operation is simplified.
However, unlike the buttonhole described in the document DE 36 12 772, the portion with a large cross-section is here located on the other side of the portion with a small cross-section. As a result, a relatively larger surface is available to house it. Moreover, the portion with a small cross-section is brought back toward the axle of the hub, resulting in a gain in rigidity and weight.